Vista Peak High School, located in Aurora, Colorado, was commissioned in 2011 as a LEED Gold Certified building. The two-story, 216,000 sq. ft. high school serves a very diverse community just east of Denver. The District’s 40,000 students represent immigrant families from over 131 different countries and proudly ranks second highest in the State for dual enrollment —college-credited coursework— programs.
The opportunity to reduce costs, even for LEED Gold Certified buildings, is always welcomed, especially when it comes to offsetting the tight operational budget of a school. So when Vista Peak was offered a place in Xcel Energy’s Building Optimization Pilot program —which is focused on energy optimization for large buildings— they jumped at the opportunity and installed BuildingIQ’s Predictive Energy Optimization™ (PEO) software in August 2015.
The primary challenge was that the energy efficiency performance of the school’s building had deteriorated significantly, despite being relatively new and LEED Gold Certified. Energy intensity (electric and gas consumed per square foot) had nearly doubled in four years – climbing from 35,000 BTU/sq. ft. in 2011 – when the building was first commissioned – to 65,000 BTU in 2015. The reasons for the deterioration were not apparent, and there was insufficient trend data for thorough analysis of the problem.
PEO maximizes savings and operational efficiency by predicting, and then executing, optimized building management system HVAC sequences. Initial testing revealed that Vista Peak’s system had not only drifted, but was also unable to respond to PEO determined sequencing. Under normal conditions, PEO intelligently determines the optimal balance between energy savings and comfort on an hour-byhour basis 24/7. In the case of Vista Peak, the BMS was not responding as expected.
“My speculation was that there was something wrong with the way the air handlers were operating,” said Craig Wright, Energy Manager for the Aurora Public Schools. “We have 12 major air handling units, each supplying about 20,000-25, 000 cfm of air, and likely deterioration of instrumentation crucial for air flow measuring allowed the set points to migrate over time, causing many control parameters to fall out of calibration.”
All buildings go through a “make ready” process so that PEO can be connected and configured to work with the existing BMS. It was at this stage —in the fall of 2015— that BuildingIQ’s Managed Services team established a close relationship with Aurora’s building automation team. The first steps were to analyze the building’s energy efficiency performance, and to identify and rectify any performance problems.
“I was excited to get the granularity of data available through BuildingIQ’s PEO,” said Wright. “The fact that BuildingIQ trends so many different variables associated with air handlers,
supply air temperatures, hot and chilled water valve positioning, among others, give us the means to unravel problems. Their data allows us to understand thoroughly how the space is reacting to the equipment and how the equipment is reacting to the programming.” By January 2016, the Managed Services team had generated enough trend data and information on various anomalies in the HVAC system for the two teams to diagnose underlying issues. “It was pretty revealing to see just how out of synch the various elements of the HVAC system were,” said Wright.
Although optimized when the building opened in 2011, small discrete modifications to the programming were deemed necessary. “We took it upon ourselves to dig into the programming problems. We can see the value that will ultimately be delivered. The visualization of real-time data through BuildingIQ’s platform will help us fine-tune the control sequences.”
The collaborative, consultative nature of the two technical teams —Aurora’s and BuildingIQ’s— helped reveal some fundamental problems beyond set-point recalibration that are hindering optimum performance of the HVAC system.
In particular, they found simultaneous heating and cooling taking place. The heating coil was controlling the heating in the morning but around noon it was turning to a pre-cooling function. The result is that the BMS is sometimes trying to heat and cool the building at the same time. The suggested actions now being considered by the Aurora’s team are to correct the BMS programming of the AHU to prevent this conflict in mission. Programming should make decisions more definitive; such that when the heating is active cooling is locked out.
Similarly, when cooling is active heating should be locked out. The complimentary roles of the two teams will serve Vista Peak well over the long term. BuildingIQ’s analytical capabilities and Aurora’s intimate knowledge of the school facilities are mutually reinforcing. Through joint action, energy performance can be brought back to the performance that provided the initial LEED Gold standard, and perhaps taken to a higher level (Read our white paper “Energy Efficiency Ratings— Benchmarks that Drive Excellence in Building Design and Operations” to learn how BuildingIQ can potentially contribute to increasing a building’s LEED points). Optimization software involves on-going learning and leads to continuous fine-tuning. The result will be not only energy savings but also a positive cash-flow contribution to Aurora’s school budget.
“BuildingIQ trends so many different
variables associated … (to) give us the means to unravel problems.”
cash-flow contribution to Aurora’s school budget.
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